The later structure of the epidermis is the morphological expression of the step wise differentiation and maturation process toward cell keratinization. In the stratum spinous and stratum granulosum intercellular processes lead to the formation of the stratum corneum. 




The skin's surface has various features, for example, furrows, wrinkles, lines, ridges, and plains are all examples of what can be found on the surface of your skin. In the course of life, increasing amounts of furrows and wrinkles are formed in what started as smooth child's skin. Furrows are wrinkles caused by moving appear at the joints. Age-related wrinkles and furrows appear as signs of the aging of the skin or the linked emotions on the account of the mimetic facial musculature (laughter lines, frown lines.) The skin surface is covered by a complex hydrolipidic film (skin surface film) that consists primarily of sweat glands and sebaceous glands and houses the physiological flora of the skin.


Skin color (also complexion) is an individual characteristic that is determined above all by the pigmentation of the skin and the structure of the blood vessels. Various pigments have an effect on the color of the skin. The quantity of melanin is a particular decisive factor in humans. The color of the skin, whether fair, medium, or dark, depends in part on the blood supply to the skin, and primarily on the melanin, or coloring matter, which is deposited in the stratum germinativum and the papillary layers of the dermis. The pigment's color varies in different people. The distinctive color of the skin is a hereditary trait and varies among races and nationalities. The amount of melanin in the skin is genetically determined, but more melanin is also produced under exposure to sunlight (UV rays) within a certain wavelength. There are two types of melanin: one is eumelanin, a brown-to-black pigment, and the other is pheomelanin, a red-to-yellow pigment. Eumelanin determines the skin type and with this the skin color. Pheomelanin then produces, especially in people with light skin types, a reddish or yellowish undertone. Red hair is a clear indicator that much more pheomelanin than eumelanin is being produced. This is why the extremely Light Skin Type I is mainly associated with red hair. 


  • Protection

  • Sensation

  • Heat Regulation

  • Exertion

  • Secretion


The skin protects the body from injury and bacterial invasion. The outermost layer of the epidermis is covered with a thin layer of sebum, thus rendering it waterproof. It is resistant to wide variations in temperature, minor injuries, chemically active substances, and many microbes.


Through its sensory nerve endings, the skin responds to heat, cold, touch, pressure, and pain. Extreme stimulation of sensor nerve endings produces pain. A minor burn is very painful, but a deep burn that destroys nerves may be painless. Sensory endings, responsive to touch and pressure, and situated near hair follicles.


The healthy body maintains a constant internal temperature of about 98.6 degrees Fahrenheit (37 degrees Celsius.) As changes occur in the outside temperature, the blood and sweat glands of the skin make necessary adjustments in their functions. Heat regulation is a function of the skin, the organ that protects the body from the environment. The body is cooled by the evaporation of the sweat.


Perspiration from the sweat glands is excreted from the skin. Water lost by perspiration carries salt and other chemicals with along with it.


Sebum is secreted by the sebaceous glands. Excessive flow of oil form the oil glands may produce seborrhea. Emotional stress may increase the flow of sebum. 


This function is limited, but it does occur. Female hormones, when an ingredient of a face cream, may enter the body through the skin and influence it to a minor degree. Fatty materials, such as lanolin cream, are absorbed largely through the hair follicles and sebaceous gland openings. 


Melanocytes are the pigment-producing cells of the skin and are located in the basal cell layer of the epidermis and in the hair follicles. They synthesis melanin and pass in the form of what are called melanosomes to the surrounding keratinocytes. Melanin delivers important skin protection against UV rays. Melanin-producing cells together with the surrounding keratinocytes form what is called a melanocyte unit. Skin color is not determined by an increase in the quantity of melanocytes, rather to a much greater degree by how long melanosomes remain in keratinocytes. 


The skin protects against heat loss and external influences and service to detect tactile stimuli. The individual components of the skin also perform specialized functions:

  • Hair: protects against heat loss and the rays of the sun

  • Horny Layer: protects against injury and dehydration

  • Melanocytes: protect the genetic information in cell nuclei against UV rays

  • Free Nerve Endings: reception of tactile stimuli and sensations of pain

  • Lamellar Corpuscles: reception of pressure stimuli

  • Cold Receptors: reception and cold stimuli

  • Hair: protects against heat loss and the rays of the sun

  • Horny Layer: protects against injury and dehydration

  • Melanocytes: protect the genetic information in cell nuclei against UV rays

  • Free Nerve Endings: reception of tactile stimuli and sensations of pain

  • Lamellar Corpuscles: reception of pressure stimuli



The skin is a surface organ (not a compact organ) that covers and protects the outside of the organism (it is an integument.) The cutis consists of the epidermis and dermis. Its total area is around 1.5 to 2m (adult) and it is between around 1 and 4mm thick (excluding the subcutis.) The outer skin transforms into the mucous membrane of the body's inner surface at the body orifices. From outermost to innermost, the ski, also known as the cutis, consists of the following layers as listed below. The skin is bounded by the general fascia, which consists of very strong fibers known as collagen fibers.

  • Epidermis

  • Dermis or corium

  • Subcutis or hypodermis


  • Statum corneum or horny layers

  • Stratum lucidum or clear layer

  • Statum granulosum or granular cell layer

  • Stratum spinous or spinous layer

  • Stratum basale or basal cell layer

Avascular, outermost layer of the skin (cutis) of ectodermal origin; consists of stratified keratinized epithelia ( 4 layers, 5 on the hand and feet); thickness between 30pm and 4mm, depending on the region of the body. The layers are as listed below:

1. Stratum basale (cylindreur) basal cell layer; prismatic cells that are attached to the subepidermal basal membrane via protoplasma feet, contain melanin pigments

2. Stratum spinosum: spinous layer; 4-8 layers of polygonal cells bound together via cytoplasmic projections (known as prices.) Stratum basal and stratum spinous are together called the stratum germinativum (germinative layer), since it is here that, via a process of cell division (primarily in the stratum basale), the replacement of keratinized cells shed from the surface of the epidermis takes place. The stratum germinativum is composed of several layers of several different shaped cells. The deepest layer is responsible for the growth of the epidermis. It also contains a dark skin pigment called melanin, which protects the sensitive cells below from the destructive effects of excessive UV rays of the sun or of an UV lamp. 

3. Stratum granulosum: granular cell layer; 1-5 layers of flattened cells with very basophilic refractive keratohyalin granules. This granular layer consists of cells that look like distinct granules. These cells are almost dead and undergo a change into a horny substance.

4. Stratum lucidum: clear layer; built up only where the epidermis is thick (palm of the hand, soles of the feet) anucleated, ill-defined cells with very refractive acidophilic eleidin. This is the clear layer that consists of small transparent cells through which light can be passed.

5. Stratum corneum: horny layer; flat, anucleated, keratinized cells (stratum conjunctum) that are shed from outer surface in fine flakes (stratum disjunctum.) The inner surface of the epidermis has a network of ridges (retentions ridges.) Between these ridges lie valleys that catch the papillae of the dermis. The epidermis is supplied with the nutrients via the blood capillaries of the papillae. This is the horny layer of the outer layer of the skin. Its scale-like cells are continually being shed and replaced by underlying cells coming to the surface. These cells contain keratin, a protein substance. The overlapping cells are covered by a thin layer of oil which helps make the stratum corneum almost waterproof.


The Dermis is an elastic layer of skin that consists largely of loosely woven connective tissues. It also in turn consists of layers, namely the stratum papillae or papillary Subcutia and stratum reticular or lattice layer. The Subcutis consists of loose connective tissue in which fat pads are integrated like little cushions. The connective tissue is traversed by offshoots of the strong fibers of the dermis. These fibers are firmly attached to the fascia that lie under the cutis. They thereby perform the function of retainer bands, binding the skin of the tissue that lies beneath. The dermis is the true skin. It is a highly sensitive and vascular layer of connective tissue. Within its structure are found numerous blood vessels, lymph vessels, nerves, sweat glands, oil glands, hair follicles, arrector pili muscles and papillae. The dermis consists of two layers: the papillary, or superficial layer, and the reticular, or deeper layer.

Subcutaneous tissue is a fatty layer found below the dermis. This tissue is also called adipose or subcutis tissue and varies in thickness according to the age, sex, and general health of the individual. It gives smoothness and contour to the body, contains fats for use as energy, and also acts as a protective cushion for the outer skin. Circulation is maintained by a network of arteries and lymphatics. 



A lesion is a structural change in the tissues caused by injury or disease. There are three types:

  • Primary

  • Secondary

  • Tertiary

The intradermal cosmetic technician is concerned with primary and secondary lesions only. Knowing the principal skin lesions helps the intradermal cosmetic technician to distinguish between conditions that may or may not be treated in the clinic setting. A symptom is a sign of disease. The symptoms in diseases of the skin are divided into two groups, 1 and 2.

1. Subjective refers to symptoms that can be felt, as itching, burning, or pain

2. Objective refers to Symptoms that can be seen, as pimples, pustules or inflammation


A blister containing a watery fluid, similar to a vesicle, but larger


A small, discolored spot or patch on the surface of the skin, neither raised nor sunken, as freckles


A small, elevated pimple in the skin, containing no fluid but which may develop pus.


An elevation of the skin having an inflamed base, containing pus.


A solid lump or larger than a papule. It projects above the surface or lies within or under the skin. It varies from the size of a pea to a hickory nut.


An external swelling, varying in size, shape and color.


An itchy, swollen lesion that lasts only a few hours. (Example, hives, or the bite of an insect such as a mosquito.)


A blister with a clear fluid in it. Vesicles lie within or just beneath the epidermis. (Example, poison ivy process small vesicles.)



An accumulation of serum and pus, mixed perhaps with epidermal material. Ex: the scab on a sore.


A skin sore or abrasion produced by scratching or scraping. Ex: a raw surface due to the loss of the superficial skin after an injury


A crack in the skin penetrating into the derma, as in the case of chapped hands or lips.


An accumulation of epidermal flakes, dry or greasy. Ex: abnormal or excessive dandruff.


Likely to form after the healing of an injury or skin condition that has penetrated the dermal layer


An abnormal discoloration remaining after the disappearance of moles, freckles, or liver spots, sometimes apparent after certain diseases


An open lesion on the skin or mucous membrane of the body, accompanied by pus and loss of skin depth


Any departure from a normal state of health


One manifested by symptoms of a more or less violent character and of short duration


One of long duration, usually mild, but recurring


One that is communicable by contact


One due to pathogenic germs taken into the body as a result of contact with a contaminated object or lesion


Any infection of the skin which can be characterized by an objective lesion (one that can be seen)


A sensitivity that certain persons develop to normally harmless substances (cosmetics, medicines, etc)


One that is present in the infant at birth


The manifestation of a disease that attacks simultaneously a large number of persons living in a particular locality


A skin disorder characterized by redness, pain, swelling, and heat


One that is due to certain kinds of employment and is caused by coming in contact with cosmetics, chemicals, etc.


One produced by a disease-causing bacteria, such as staphylococcus and streptococcus, puss-forming bacteria


One that is influenced by the weather, as prickly heat in the summer, and forms of eczema, which are more prevalent in cold weather


Due to under or over-functioning of the internal glads. It may be caused by faulty diet.


A contagious disease commonly acquired by contact with an infected person during sexual intercourse.




An acquired, superficial, round, thickened patch of epidermis, due to pressure friction on the hands and feet. If thickening grows inward, it is called corn.


A small, brownish spot, or blemish on the skin. Miles are believed to  be inherited. They range in color from pale tan to brown or bluish black. Some moles are small and flat, resembling freckles, while others are more deeply seated and darker in color. Large, dark hairs often occur in moles. Any change in a mole requires medical attention. CAUTION: Do not treat or remove hair from moles.


Technical term for a wart. It is caused by a virus and is infectious. It can spread from one location to another, particularly along a scratch in the skin.


A disorder causing baldness in spots. This condition may be treated under the direction of a physician. Alopecia refers to a condition of premature baldness or excessive hair loss. The chief causes of alopecia are poor circulation, lack of proper stimulation, improper nourishment, certain infectious skin diseases, such as ringworm, or constitutional disorders. The treatment of alopecia is directed to stimulating the blood supply to the scalp and reviving the hair papillae involved in hair growth.



This information has been compiled to help the intradermal cosmetic technician become familiar with certain common skin disorders with which they may come into contact. Any client with a skin condition that the technician does not recognize to be a simple disorder should be referred to a physician. The most important thing to know is that a client who has an inflammatory skin disorder, which may or may not be infectious, should be treated.


Listed below are a number of important terms with which the intradermal cosmetic technician should be familiar.


The study of the skin, its nature, structure, functions, disease, and treatment.


A skin specialist.


Is the recognition of a disease by its symptoms.


The study of the causes of disease.


The study of disease.


The foretelling of the probable course of the disease.


The study of hair and its diseases.

Disclaimer of Medical and Legal Liability: Scalpa training courses are intended to provide the general knowledge to perform procedures but is not intended to be a substitute for medical advice, diagnosis or treatment. Reliance on the information in this training course for procedural purposes is to be used at your own risk. If you have questions or concerns, contact a medical professional prior to treatment. Scalpa is not held responsible or liable for risks involved with this procedure. 


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